Solar water heating system

ABSTRACT

A solar water heating system employs at least one solar heat collector having an upper manifold, a lower manifold, and at least one fluid passage between the upper and lower manifold. The upper and lower manifolds each are inclined, so that air within the manifolds travels to the manifolds upper ends. A liquid reservoir, located above the collector, has an outlet at a bottom portion and a supply inlet at an upper portion. A float valve within the liquid reservoir maintains a constant hydrostatic head pressure at the reservoir output. An air vent is connected between the collector and the liquid reservoir so that air bubbles within the collector vent to the liquid reservoir. A metering valve varies the flow rate of liquid from the solar heat collector, thereby varying dwell time of liquid within the collector. The system may be evacuated entirely to a benchmark water level.

FIELD OF THE INVENTION

The present invention relates to a solar heating system, and moreparticularly to a solar water heating system for swimming pools.

BACKGROUND

Solar heating systems employ solar radiation to heat a fluid medium totransfer heat for a heating application, such as heating of aresidential or commercial building, heating of a swimming pool, or otherapplications. Commonly, the fluid medium is a liquid, such as water. Ina typical arrangement, a solar heat exchanger employs an upper manifoldand a lower manifold, the manifolds being connected by at least onefluid passage wherein a liquid is heated by solar radiation as theliquid travels along the fluid passage between the manifolds.

Generally, a liquid flows either from the lower manifold to the upper,or from the upper manifold to the lower. In either case, air bubblescollect within the manifolds, within the fluid passages connecting themanifolds, and within other parts of a solar heating system thatincorporates the solar heat exchangers. Formation of air bubbles isfound particularly within the solar heat exchanger as the liquid isheated.

Air trapped within the solar heating system prevents optimum heating ofthe liquid, and contributes to mechanical stresses on the solar heatexchangers that may ultimately cause the heat exchanger to leak or fail.

Air within a heat exchanger may become trapped against an upper part orsurface of the heat exchanger and thus insulate the liquid from theheating of solar radiation. This prevents the maximum transfer of solarenergy to the liquid, decreasing the efficiency of the solar heatexchanger.

Vibrations caused by air bubbles traveling through a solar heatingsystem, and exiting the solar heating system such as into a swimmingpool, result in vibration of various components of the solar heatingsystem including the heat exchangers. These vibrations cause wear on thecomponents of the solar heating system, and particularly on the heatexchangers, contributing to a shortened useful life of the solar heatingsystem. Additionally, vibrations caused by air within the system causesnoise during operation of the system.

SUMMARY

A solar water heating system for heating a liquid drawn from andreturned to a liquid source, such as a swimming pool, employs at leastone solar heat collector to heat the liquid using solar energy. Thesolar heat collector has an upper manifold and a lower manifold, and atleast one fluid passage between the upper and lower manifold in agenerally conventional arrangement. The upper and lower manifolds eachare inclined, each having an upper end and a lower end, so that airbubbles within the solar heat collector will travel to the upper ends ofthe upper and lower manifolds.

A liquid reservoir is located at an elevation above the solar heatcollector, the reservoir having an outlet at a bottom portion of thereservoir and a supply inlet at an upper portion of the reservoir. Theoutlet is coupled to the upper end of the upper manifold so that liquidwithin the reservoir may flow by gravity into the solar heat collector.A float valve may be employed within the reservoir to maintain aconstant hydrostatic head pressure at the reservoir output.

An air venting conduit is connected between the solar heat collector andthe reservoir so that air bubbles trapped or formed within the solarheat collector are vented to the reservoir.

A fluid supply conduit has a first end in fluid communication with thesupply inlet of the reservoir and a second end in fluid communicationwith the liquid source, to supply a liquid medium from the liquid sourceto the reservoir, and a fluid returning conduit has a first end in fluidcommunication with the solar heat collector and a second end in fluidcommunication with the liquid source to return heated liquid to theliquid source.

A metering valve may be disposed inline of the fluid returning conduitto vary the flow rate of liquid from the solar heat collector, and tothereby vary the dwell time of liquid within the solar heat collector.

A pump may be provided to draw liquid from the liquid source and pumpthe liquid to the reservoir.

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a solar heating system according to thepresent invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

The present invention is a solar water heating system, designatedgenerally as 100 in the drawings. A liquid is supplied to the solarwater heating system 100 from a liquid source, heated by the solar waterheating system 100, and returned to the liquid source. Referring to FIG.1, an embodiment of the solar water heating system 100 is shown whereinthe liquid source is a swimming pool 110, and the solar water heatingsystem 100 is functionally connected with the swimming pool 110 forheating water for the swimming pool 110.

It can be appreciated that, in alternative embodiments, the solar waterheating system 100 may be readily adapted to other heating applications,including closed circuit applications wherein a liquid is contained andcirculated within a closed circuit that includes a heat transferringapparatus to conduct heat from the solar water heating system 100 for aheating application.

In a typical configuration, a swimming pool 110 may be associated with ahot tub or spa 112 or the like, the swimming pool 110 and spa 112 beingserviced together by a filtration system including a conventional pump114 and a filter 116. In the configuration shown in FIG. 1, the pump 114draws water from the swimming pool 110 via a pump supply line 115, andpumps the water through the filter 116. The water is returned to theswimming pool 110 from the filter 116 by a filter return conduit 117.One-way check valves 168 of conventional design are shown to preventbackflow of water through the pump 114, filter 116, and the solar waterheating system 100. It can be recognized that alternate configurationsare possible.

The solar water heating system 100 comprises at least one solar heatcollector 120, and a pressure regulator 140. While the solar waterheating system 100 is illustrated with a single solar heat collector120, additional solar heat collectors 120 may be employed. An example ofa suitable solar collector useful for this invention is marketed underthe name SunGrabber™ by FAFCO, Inc. Corporation of Chico, California,model 07295. The pressure regulator 140 regulates the hydrostatic headpressure of liquid that is fed, by gravity, into the solar heatcollector 120. A liquid is supplied to the pressure regulator 140 from aliquid source. In the presently illustrated embodiment, liquid issupplied from the filter return conduit 117 to the solar water heatingsystem 100 by a supply conduit 118 that is connected to a supply valve119 of conventional design connected inline of the filter return conduit117. It can be understood that the supply conduit 118 may be alternatelyconfigured to draw liquid from a liquid source. Thus, opening the supplyvalve 119 allows some of the liquid pumped by the pump 114 to be fedinto the solar water heating system 100, thereby supplying the pressureregulator 140 with liquid from the liquid source, such as, in theillustrated embodiment, water from the swimming pool 110.

The solar heat collector 120 comprises an upper manifold 122 and a lowermanifold 132, the upper manifold 122 being positioned at an elevationabove the lower manifold 132. The upper manifold 122 is connected to thelower manifold 132 by at least one fluid passage 130 in a generallyconventional manner whereby a liquid supplied to the upper manifold 122is heated by solar heating as the liquid passes through at least onefluid passage 130 to the lower manifold 132.

Each of the upper and lower manifolds 122, 132 are inclined, such thatthe upper manifold 122 has an upper end 124 and a lower end 126, and thelower manifold 132 has an upper end 134 and a lower end 136. Because ofthe incline of each of the manifolds 122, 132, air within the solar heatcollector 120 will move toward the upper ends 124, 134 of the upper andlower manifolds 122, 132 respectively as the air bubbles tend to risealong the inclined manifolds 122, 132.

A liquid is supplied to the solar heat collector 120 for heating fromthe pressure regulator 140. The pressure regulator 140 is located at anelevation above the highest point of the solar heat collector 120. Theliquid is fed by gravity from the pressure regulator 140 at ahydrostatic head pressure that is determined by the liquid level withinthe pressure regulator 140.

The pressure regulator 140 comprises a reservoir 142 and a float valve144. At least a float member 146 of the float valve 144 is disposedwithin the reservoir 142. The float member 146 is connected by anappropriate lever to the valve 144, for example a simple flapper valveor other suitable design, and is movable between a lower position 148 a,where the float valve 144 is fully opened, and an upper position 148 bwhere the float valve 144 is fully closed. At intermediate positions ofthe float member 146, the float valve 144 is partially open in relationto the position of the float member 146. Thus, liquid supplied to thesolar water heating system 100 enters the reservoir 142 through thefloat valve 144 at a flow rate related to the liquid level within thereservoir 142.

The float valve 144 regulates liquid flow into the reservoir 142 tocompensate for liquid flowing out of the reservoir 142 and into thesolar heat collector 120 so that a constant hydrostatic head pressure ismaintained within the solar heat collector 120. The liquid flows from anoutlet 150 of the reservoir, located at the bottom or a lower portion ofthe reservoir 142, to the upper end 124 of the upper manifold 122 of thesolar heat collector 120. The liquid flows from the upper manifold 122,through the fluid passage 130 wherein the liquid is heated, and out fromthe lower end of the lower manifold 132. The head pressure could bevaried by adjusting the fluid level in reservoir 142 or varying theelevation of the reservoir.

A fluid return conduit 154 connects the lower end 136 of the lowermanifold 132 of the solar heat collector 120 to the swimming pool 110 toreturn heated water to the swimming pool 110. A manually adjustablemetering valve 156 of conventional design is provided inline of thefluid return conduit 154 so that the rate of flow of liquid from thesolar heat collector 120 may be varied. By varying the rate of flow ofliquid from the solar heat collector 120, the dwell time of the liquidwithin the solar heat collector 120 may be varied, allowing for controlover the temperature of the liquid exiting the solar heat collector 120.Additionally, the metering valve 156 may be adjusted such as to decreasethe flow rate from the reservoir 142 or through the solar heat collector120 in the event that the flow rate through the float valve 144 into thereservoir 142 is less than the gravity flow rate through the reservoir142 or through the solar heat collector 120.

In the illustrated embodiment, a two-way valve 166 of conventionaldesign is employed in the fluid return conduit 154 to selectivelydeliver heated water from the solar heat collector 120 to either theswimming pool 110 or the spa 112, or both. It can be recognized thatadditional configurations are possible.

An air vent line 158 is connected to the upper end 124 of the uppermanifold 122 to allow air to be vented from the system. Additionally,the air vent line 158 may be connected to the upper end 134 of the lowermanifold 132 to allow air to be vented directly from the lower manifold132, as shown in the illustrated embodiment. Alternate arrangements maybe employed, such as a single air vent line in connection with both theupper and lower manifolds 122, 124, separate air vent lines for each ofthe upper and lower manifolds 122, 124, or an air vent line connectedonly to the upper end of the upper manifold 122, with a fluid passageprovided between the upper end 134 of the lower manifold 132 and theupper manifold 122 such that air collected at the upper end 134 of thelower manifold 132 will pass to the upper manifold 122 rather thancollect in the lower manifold 132.

The air vent line 158 vents air from the solar heat collector 120 intothe reservoir 142. A float activated check valve 160 is located in thetop, or an upper portion, of the reservoir 142. Under normal operatingconditions, the float activated check valve 160 is open so that airvented from the solar heat collector 120 is allowed to exit from thereservoir 142 to the atmosphere.

An overflow conduit 162 is connected to the top, or an upper portion, ofthe reservoir 142. The overflow conduit 162 returns liquid overflow fromthe reservoir 142 to the swimming pool 110. In the event that the liquidflow into the reservoir 142 exceeds the liquid flow from the reservoir142, such as if the float valve 144 malfunctions, an increase of theliquid level within the reservoir 142 as the reservoir 142 fills causesthe float activated check valve 160 to close as the float is raised bythe liquid, preventing liquid spillage from the reservoir 142. Excessliquid is then returned to the swimming pool 110 by way of the overflowconduit 162. An outlet end 164 of the overflow conduit 162 is preferablylocated above the water level of the swimming pool 110 to discharge theliquid overflow into the atmosphere above the water level of theswimming pool 110 so that a noise is created by the overflow liquiddischarging into the swimming pool 110, audibly drawing attention to theoverflow condition.

In a solar heating system 100 according to the present invention,mechanical stresses of the solar heating system, and particularly of thesolar heat collector 120, are reduced by the elimination of aircollected within the system, because vibrations caused by circulation ofair and air bubbles is reduced or eliminated. Additionally, becauseliquid is delivered to the solar heat collector 120 by a gravity flowunder a controlled hydrostatic head pressure, fluid pressures within thesolar heat collector 120 are lower than in systems wherein a liquid ispumped under pressure through a solar heat exchanger.

A liquid level controlling device 170, such as of a type commonly knownand used in swimming pool installations, may be used to maintain aproper, and constant, benchmark water level 172 in the swimming pool110. When a liquid supply pressure is removed from the system, such asby deactivating the pump 114 or by closing the supply valve 119, thesolar heating system 100 may be drained entirely down to the benchmarkwater level 172.

It will be understood that the above-described embodiments of theinvention are illustrative in nature, and that modifications thereof mayoccur to those skilled in the art. Accordingly, this invention is not tobe regarded as limited to the embodiments disclosed herein, but is to belimited only as defined in the appended claims.

1. A solar water heating system for heating liquid drawn from a liquidsource, the solar water heating system comprising: at least one solarheat collector having an upper manifold and a lower manifold and atleast one fluid passage between the upper and lower manifold, the upperand lower manifolds each being inclined and each having an upper end anda lower end; a liquid reservoir located at an elevation above said solarheat collector, the liquid reservoir having an inlet and an outlet, theoutlet being coupled to the upper end of said upper manifold; an airventing conduit providing fluid communication between the upper end ofsaid upper manifold and said liquid reservoir; a fluid supply conduitproviding fluid communication between the supply inlet of said liquidreservoir and said liquid source; and a pump disposed inline in saidfluid supply conduit between said liquid source and said liquidreservoir, the pump being adapted to draw liquid from the liquid sourceand pump the liquid to said liquid reservoir.
 2. The solar water heatingsystem according to claim 1, wherein said air venting conduit is coupledto an upper portion of said liquid reservoir.
 3. The solar water heatingsystem according to claim 1, further comprising an air venting conduitcoupled between the upper end of said lower manifold and said liquidreservoir.
 4. The solar water heating system according to claim 1,wherein said liquid reservoir further comprises a check valve located atan upper portion of said liquid reservoir, the check valve being adaptedto vent air from said reservoir while preventing liquid from overflowingthrough the check valve.
 5. The solar water heating system according toclaim 1, further comprising a fluid returning conduit providing fluidcommunication between the lower end of said lower manifold and saidliquid source.
 6. The solar water heating system according to claim 5,further comprising a metering valve disposed inline in said fluidreturning conduit.
 7. The solar water heating system according to claim1, further comprising a float activated valve disposed between saidfluid supply conduit and said liquid reservoir, the float activatedvalve being adapted to control the flow of liquid from said fluid supplyconduit into said liquid reservoir according to a liquid level withinsaid liquid reservoir.
 8. The solar water heating system according toclaim 7, wherein said float activated valve includes an activating floatdisposed within said liquid reservoir.
 9. The solar water heating systemaccording to claim 1, further comprising a liquid overflow conduithaving a first end coupled to said liquid reservoir and a discharge end.10. The solar water heating system according to claim 9, wherein thedischarge end of said overflow conduit is located above said liquidsource whereby an overflow liquid discharged from the discharge end isaudibly returned to said liquid source.
 11. A solar water heating systemfor heating liquid drawn from a liquid source, the solar water heatingsystem comprising: at least one solar heat collector having an uppermanifold and a lower manifold and at least one fluid passage between theupper and lower manifold, the upper and lower manifolds each having afirst end and a second end; a pressure regulator located at an elevationabove said solar heat collector, the pressure regulator having an outletand an inlet, the outlet being coupled to the first end of said uppermanifold, the inlet being coupled to said liquid source; a fluidreturning conduit providing fluid communication between the second endof said lower manifold and said liquid source; a metering valve disposedinline in said fluid returning conduit; and a pump coupled between saidliquid source and said pressure regulator, the pump being adapted todraw liquid from the liquid source and pump the liquid to said pressureregulator.
 12. The solar water heating system according to claim 11,wherein said pressure regulator comprises a liquid reservoir.
 13. Thesolar water heating system according to claim 12, wherein said pressureregulator further comprises a float activated valve coupling said liquidsource and said liquid reservoir.
 14. The solar water heating systemaccording to claim 13, wherein said float activated valve includes anactivating float disposed within said liquid reservoir.
 15. The solarwater heating system according to claim 11, wherein said liquidreservoir further comprises a check valve located at an upper portion ofsaid liquid reservoir.
 16. The solar water heating system according toclaim 11, wherein the upper manifold is inclined, having its first endelevated relative to its second end.
 17. The solar water heating systemaccording to claim 16, further comprising an air venting conduit coupledto the first end of said upper manifold.
 18. The solar water heatingsystem according to claim 11, wherein the lower manifold is inclined,having its first end elevated relative to its second end.
 19. The solarwater heating system according to claim 18, further comprising an airventing conduit coupled to the first end of said lower manifold.
 20. Thesolar water heating system according to claim 11, further comprising aliquid overflow conduit having a first end coupled to said pressureregulator and a discharge end in fluid communication with said liquidsource.
 21. The solar water heating system according to claim 1, whereinsaid liquid is water.
 22. The solar water heating system according toclaim 1, wherein said liquid source is a swimming pool.
 23. The solarwater heating system according to claim 1, wherein said solar heatcollector is positioned at an elevation above said liquid source.